1. Field of the Invention
The present invention relates to pharmaceutical compositions in the form of a gel for controlled- or sustained-release of a pharmaceutically active agent and to methods for treating or preventing a condition in an animal by administering to an animal in need thereof the pharmaceutical compositions. One particular type of condition for which the pharmaceutical compositions are useful is a microbial infection, e.g., of the skin, ear, or eye, especially for veterinary applications.
2. Description of Related Art
It is often desirable to administer drugs using controlled- or sustained-release formulations that can maintain at least a minimum therapeutic level, for example, a blood level, of the drug over extended periods of time. These controlled- or sustained-release formulations reduce the frequency of dosing, for enhanced convenience and compliance, and also reduce the severity and frequency of side effects. For example, by maintaining substantially constant blood levels and avoiding blood level fluctuations of the drug, such as are associated with conventional immediate release formulations that are administered several times a day, controlled- or sustained-release formulations can provide a better therapeutic profile than is obtainable with conventional immediate release formulations.
Known methods for controlled- or sustained-drug release include implanted devices, such as osmotic pumps, and drug dispersed in a biocompatible polymer matrix, which can be implanted, administered orally, or injected. Examples of biocompatible polymers used in such applications include poly(lactic acid) and poly(lactic acid-co-glycolic acid). The polymer typically undergoes slow hydrolysis in vivo to continually release the entrapped drug over time. The polymer degradation products are non-toxic and absorbed or metabolized by the body. For example, when the biocompatible polymer is poly(lactic acid) or poly(lactic acid-co-glycolic acid), the degradation products are the parent acids, lactic acid and glycolic acid, which are absorbed by the body.
U.S. Pat. No. 5,110,809 to Wang et al. discloses a stable anhydrous gel formulations for topical antifungal use containing an imidazole, a steroid, a co-solvent system comprising monohydric and dihydric alcohols, and a hydroxyalkylcellulose gellant.
International Publication No. WO 00/09117 discloses topical pharmaceutical compositions containing nimesulfide, a non-steroidal anti-inflammatory agent having poor solubility in water.
U.S. Pat. No. 6,214,339 to Pellico discloses a treatment for otitis externa in cats and dogs that comprises administering a substantially non-aqueous, di-enzymatic therapeutic composition, in a liquid or gel fluid carrier. An illustrative composition contains glucose, glucose oxidase, potassium iodide, and lactoperoxidase in a fluid mixture of glycerol and propylene glycol.
Eurasian Patent No. EA 0002978 B1 claims in the primary independent claim a process for preparing a phospholipid suspension.
There remains a need in the art, however, for drug-containing pharmaceutical compositions, especially drug-containing pharmaceutical compositions suitable for topical, otic, and ophthalmic applications, that provide controlled- and/or sustained-release of the drug contained therein.
Citation of any reference in Section 2 of this application is not to be construed that such reference is prior art to the present application.